diff --git a/MODULE.bazel b/MODULE.bazel
index a490e51b27..d5b3e174b7 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -40,7 +40,7 @@ bazel_dep(name = "rules_kotlin", version = "2.3.20")
 bazel_dep(name = "rules_license", version = "1.0.0")
 bazel_dep(name = "rules_pkg", version = "1.0.1")
 bazel_dep(name = "rules_python", version = "1.6.0")
-bazel_dep(name = "rules_rust", version = "0.69.0")
+bazel_dep(name = "rules_rust", version = "0.69.0", dev_dependency = True)
 
 bazel_dep(name = "rules_ruby", version = "0.20.1", dev_dependency = True)
 
@@ -194,7 +194,7 @@ rust.toolchain(
     versions = ["1.85.0"],
 )
 
-crate = use_extension("@rules_rust//crate_universe:extension.bzl", "crate")
+crate = use_extension("@rules_rust//crate_universe:extension.bzl", "crate", dev_dependency = True)
 crate.spec(
     package = "googletest",
     version = ">0.0.0",
diff --git a/bazel/flags/BUILD b/bazel/flags/BUILD
index 393fab95d6..9012b01649 100644
--- a/bazel/flags/BUILD
+++ b/bazel/flags/BUILD
@@ -46,7 +46,7 @@ string_list_flag(
 # This is now enabled by default.
 bool_flag(
     name = "prefer_prebuilt_protoc",
-    build_setting_default = True,
+    build_setting_default = False,
     # See https://github.com/protocolbuffers/protobuf/issues/25561
     scope = "universal",  # propagate from host to exec configuration
     visibility = ["//bazel/toolchains:__pkg__"],
diff --git a/java/core/BUILD.bazel b/java/core/BUILD.bazel
index 4cbd4732c1..2e789054c8 100644
--- a/java/core/BUILD.bazel
+++ b/java/core/BUILD.bazel
@@ -183,10 +183,7 @@ protobuf_java_export(
 protobuf_java_library(
     name = "lite_runtime_only",
     srcs = LITE_SRCS,
-    visibility = [
-        "//java/kotlin:__pkg__",
-        "//java/lite:__pkg__",
-    ],
+    visibility = ["//visibility:public"],
 )
 
 proto_library(
diff --git a/src/google/protobuf/compiler/java/full/message.cc b/src/google/protobuf/compiler/java/full/message.cc
index 819f20a44b..e3f7b82701 100644
--- a/src/google/protobuf/compiler/java/full/message.cc
+++ b/src/google/protobuf/compiler/java/full/message.cc
@@ -875,32 +875,26 @@ void ImmutableMessageGenerator::GenerateIsInitialized(io::Printer* printer) {
   // Memoizes whether the protocol buffer is fully initialized (has all
   // required fields). -1 means not yet computed. 0 means false and 1 means
   // true.
-  if (internal::IsOss()) {
-    // Leave this as non-transient in OSS to avoid breaking customers that are
-    // holding GSON wrong.
-    // TODO: Remove this in a future PBJ breaking release.
-    printer->Print("private byte memoizedIsInitialized = -1;\n");
-  } else {
-    // If the message transitively has no required fields or extensions,
-    // isInitialized() is always true.
-    if (!HasRequiredFields(descriptor_)) {
-      printer->Print(
-          "/**\n"
-          "  * @deprecated This always returns true for this type as it \n"
-          "  *   does not transitively contain any required fields.\n"
-          "  */\n"
-          "@java.lang.Deprecated\n"
-          "@java.lang.Override\n"
-          "public final boolean isInitialized() {\n"
-          "  return true;\n"
-          "}\n"
-          "\n");
-      return;
-    }
 
-    printer->Print("private transient byte memoizedIsInitialized = -1;\n");
+  // If the message transitively has no required fields or extensions,
+  // isInitialized() is always true.
+  if (!HasRequiredFields(descriptor_)) {
+    printer->Print(
+        "/**\n"
+        "  * @deprecated This always returns true for this type as it \n"
+        "  *   does not transitively contain any required fields.\n"
+        "  */\n"
+        "@java.lang.Deprecated\n"
+        "@java.lang.Override\n"
+        "public final boolean isInitialized() {\n"
+        "  return true;\n"
+        "}\n"
+        "\n");
+    return;
   }
 
+  printer->Print("private transient byte memoizedIsInitialized = -1;\n");
+
   printer->Print(
       "@java.lang.Override\n"
       "public final boolean isInitialized() {\n");
diff --git a/upb/BUILD b/upb/BUILD
index 4ce905cbbf..d8e701c131 100644
--- a/upb/BUILD
+++ b/upb/BUILD
@@ -125,6 +125,26 @@ cc_library(
     visibility = ["//hpb/bazel:__pkg__"],
 )
 
+# Aliases ######################################################################
+
+alias(
+    name = "base",
+    actual = "//upb/base",
+    visibility = ["//visibility:public"],
+)
+
+alias(
+    name = "mem",
+    actual = "//upb/mem",
+    visibility = ["//visibility:public"],
+)
+
+alias(
+    name = "message",
+    actual = "//upb/message",
+    visibility = ["//visibility:public"],
+)
+
 # Amalgamation #################################################################
 
 upb_amalgamation(
diff --git a/upb/bazel/private/BUILD b/upb/bazel/private/BUILD
index 0c7ac5d672..9ee2f21179 100644
--- a/upb/bazel/private/BUILD
+++ b/upb/bazel/private/BUILD
@@ -23,6 +23,6 @@ bzl_library(
         "//bazel/common:proto_common_bzl",
         "//bazel/common:proto_info_bzl",
         "@bazel_skylib//lib:paths",
-        "@bazel_tools//tools/cpp:toolchain_utils.bzl",
+        "@rules_cc//cc:find_cc_toolchain_bzl",
     ],
 )
diff --git a/upb/bazel/private/upb_proto_library_internal/aspect.bzl b/upb/bazel/private/upb_proto_library_internal/aspect.bzl
index 61f70a8561..b625db3eea 100644
--- a/upb/bazel/private/upb_proto_library_internal/aspect.bzl
+++ b/upb/bazel/private/upb_proto_library_internal/aspect.bzl
@@ -1,6 +1,6 @@
 """Implementation of the aspect that powers the upb_*_proto_library() rules."""
 
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
+load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")
 load("@rules_cc//cc/common:cc_common.bzl", "cc_common")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("//bazel/common:proto_common.bzl", "proto_common")
@@ -244,7 +244,7 @@ def upb_proto_aspect_impl(
         )
     else:
         proto_info = target[ProtoInfo]
-        cc_toolchain = find_cpp_toolchain(ctx)
+        cc_toolchain = find_cc_toolchain(ctx)
         feature_configuration = _get_feature_configuration(ctx, cc_toolchain, proto_info)
         files = _generate_upb_protos(
             ctx,
diff --git a/upb/bazel/private/upb_proto_library_internal/cc_library_func.bzl b/upb/bazel/private/upb_proto_library_internal/cc_library_func.bzl
index 47fc5a1cc2..90db085061 100644
--- a/upb/bazel/private/upb_proto_library_internal/cc_library_func.bzl
+++ b/upb/bazel/private/upb_proto_library_internal/cc_library_func.bzl
@@ -1,11 +1,11 @@
 """A function to compile C/C++ code, like cc_library() but from Starlark."""
 
-load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain", "use_cpp_toolchain")
+load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain", "use_cc_toolchain")
 load("@rules_cc//cc/common:cc_common.bzl", "cc_common")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 
 def upb_use_cpp_toolchain():
-    return use_cpp_toolchain()
+    return use_cc_toolchain()
 
 def cc_library_func(ctx, name, hdrs, srcs, copts, dep_ccinfos, includes = [], alwayslink = False):
     """Like cc_library(), but callable from rules.
@@ -25,7 +25,7 @@ def cc_library_func(ctx, name, hdrs, srcs, copts, dep_ccinfos, includes = [], al
 
     compilation_contexts = [info.compilation_context for info in dep_ccinfos]
     linking_contexts = [info.linking_context for info in dep_ccinfos]
-    toolchain = find_cpp_toolchain(ctx)
+    toolchain = find_cc_toolchain(ctx)
     feature_configuration = cc_common.configure_features(
         ctx = ctx,
         cc_toolchain = toolchain,
diff --git a/upb/bazel/upb_c_proto_library.bzl b/upb/bazel/upb_c_proto_library.bzl
index d09387be84..3c47e50993 100644
--- a/upb/bazel/upb_c_proto_library.bzl
+++ b/upb/bazel/upb_c_proto_library.bzl
@@ -38,7 +38,7 @@ upb_c_proto_library_aspect = aspect(
             default = Label("//upb_generator/c:toolchain"),
         ),
         "_cc_toolchain": attr.label(
-            default = "@bazel_tools//tools/cpp:current_cc_toolchain",
+            default = "@rules_cc//cc:current_cc_toolchain",
         ),
     },
     implementation = _upb_c_proto_library_aspect_impl,
diff --git a/upb/bazel/upb_minitable_proto_library.bzl b/upb/bazel/upb_minitable_proto_library.bzl
index 6a27082c68..9520a44ec8 100644
--- a/upb/bazel/upb_minitable_proto_library.bzl
+++ b/upb/bazel/upb_minitable_proto_library.bzl
@@ -53,7 +53,7 @@ upb_minitable_proto_library_aspect = aspect(
             default = Label("//upb_generator/minitable:toolchain"),
         ),
         "_cc_toolchain": attr.label(
-            default = "@bazel_tools//tools/cpp:current_cc_toolchain",
+            default = "@rules_cc//cc:current_cc_toolchain",
         ),
         "_fasttable_enabled": attr.label(default = "//upb:fasttable_enabled"),
     },
diff --git a/upb/bazel/upb_proto_reflection_library.bzl b/upb/bazel/upb_proto_reflection_library.bzl
index 77f168ef28..0a3e159807 100644
--- a/upb/bazel/upb_proto_reflection_library.bzl
+++ b/upb/bazel/upb_proto_reflection_library.bzl
@@ -37,7 +37,7 @@ _upb_proto_reflection_library_aspect = aspect(
             cfg = getattr(proto_common, "proto_lang_toolchain_cfg", "target"),
         ),
         "_cc_toolchain": attr.label(
-            default = "@bazel_tools//tools/cpp:current_cc_toolchain",
+            default = "@rules_cc//cc:current_cc_toolchain",
         ),
     },
     implementation = _upb_proto_reflection_library_aspect_impl,
diff --git a/upb_generator/minitable/generator.cc b/upb_generator/minitable/generator.cc
index 54f8490ce4..801c58a8b2 100644
--- a/upb_generator/minitable/generator.cc
+++ b/upb_generator/minitable/generator.cc
@@ -297,7 +297,7 @@ void WriteExtension(const DefPoolPair& pools, upb::FieldDefPtr ext,
   if (!options.one_output_per_message) {
     output("static ");
   }
-  output("const upb_MiniTableExtension $0_obj = {\n  ", ExtensionVarName(ext));
+  output("const UPB_RETAIN upb_MiniTableExtension $0_obj = {\n  ", ExtensionVarName(ext));
   output("$0,\n", FieldInitializer(pools, ext));
   output("  $0,\n", GetSub(ext, true, options));
   output("  &$0,\n", MessageVarName(ext.containing_type()));